Cranial Infection Flashcards
A 35-year-old transplant patient develops headache, neck stiffness, photophobia and fever. Cerebrospinal fluid (CSF) testing with India ink stain reveals a fungal infection. Which one of the following is the cause of this patient’s fungal meningitis?
a. Aspergillus
b. Blastomyces
c. Candida
d. Cryptococcus
e. Mucor
d. Cryptococcus
Cryptococcosis is usually acquired through the lungs and spreads to the CNS through the bloodstream. In the CNS, it may produce either a meningitis or a meningoencephalitis. Other examples include histoplasma, and candida (very rare and usually in premature babies). Fungal CNS infections occur in immunodeficiency states (e.g. AIDS, or immunosuppressive drugs, lymphoproliferative disorders). Aspergillus, Candida, Mucor, and Rhizopus can also cause CNS fungal infections, but rarely meningitis. Aspergillus tends to cause abscesses in immunocompromised indi- viduals, and Mucor affects mostly diabetics.
An 82-year-old previously healthy female with a recent history of upper respiratory tract infection presents with generalized weakness, headache, and blurry vision. Other symptoms include fever, vomiting and eye pain on movement with mild photosensitivity. She has no drug allergies. Examination findings include temperature of 102.5 °F (39.1 °C), nuchal rigidity, and drowsiness GCS is E3V4M5. Her blood pressure is 82/56 and she is tachycardic, with only a transient response to fluid challenge. Which one of the following is the next most appropriate action in this case?
a. Cranial imaging then perform a lumbar
puncture
b. Give the patient a prescription for oral co-
amoxiclav (Augmentin)
c. Immediately start intravenous antibiotics
d. Immediately start oral dexamethasone
e. Obtain CSF and blood cultures and
observe the patient in high dependency
unit the results come back
c. Immediately start intravenous antibiotics
This patient has presented with probable meningitis, but with evidence of septic shock hence antibiotics should be administered at the resuscitation stage after taking blood cultures. Cranial imaging should be performed before a lumbar puncture (at least when no previous imaging is available), but delaying antibiotics until this has all been done could be catastrophic.
A 9-year-old is brought into the emergency room lethargic with a stiff neck and fever. Despite aggressive therapy in the ITU the child dies. Postmortem evaluation reveals that the child had primary amoebic meningoen- cephalitis. This condition is usually acquired through which one of the following means?
a. Animal bites
b. Drinking contaminated water
c. Eating contaminated meat
d. Freshwater swimming
e. IV drug abuse
d. Freshwater swimming
Primary amoebic meningoencephalitis (PAM) is caused by Naegleria fowleri found in warm bodies of freshwater, and although rare is nearly always fatal. The parasites enter the nervous system through the cribriform plate at the perforations for the olfactory nerves.
A 27-year-old man presents to his primary care doctor with a low-grade fever, headache, and neck stiffness, which have become more bothersome over the past 1-2 weeks. Serum is positive for Borrelia burgdorferi IgM. CSF polymerase chain reaction (PCR) is also positive for this organism. The cranial nerve most commonly affected in this disease is most likely?
a. Abducens nerve
b. Facial nerve
c. Glossopharyngeal nerve
d. Oculomotor nerve
e. Trigeminal nerve
b. Facial nerve
Facial weakness may be the only neurological sign of Lyme disease, and may be bilateral. The neurological deficits usually appear weeks after the initial rash. The facial palsy or optic neuritis that develops with CNS disease is characteristically associated with meningitis. B. burgdorferi is a spirochete usually transmitted to humans through tick bites. Another feature is erythema chronicum migrans, an expanding reddish discoloration of the skin that spreads away from the site of the bite as a ring of erythema; evolving over 3-4 weeks then spontaneously clearing. If there is meningeal involvement, high-dose intravenous antibiotics is given for 10-14 days.
An 11-year-old girl is bitten on her upper arm by a stray dog while on holiday in South America. Two weeks later she develops throat spasms and confusion. Which one of the following is most accurate regarding the causative virus?
a. Cause of death is usually dehydration
b. Commonly causes progression to quadriplegia in 80%
c. Inducing an artificial coma obviates the
need for post-exposure prophylaxis
d. Post-exposure prophylaxis consists of a
vaccine
e. Spreads retrogradely in peripheral nerves
e. Spreads retrogradely in peripheral nerves
Rabies virus is usually spread through the saliva of an infected animal (e.g. dogs, bats, skunks, foxes, and raccoons). After introduction of the virus, the incubation period until fulminant infection appears extends from a few days to over 1 year, but usually ranges from 1 to 2 months. Bites of the head and face carry the greatest risk of causing fatal disease. Early after exposure, the patient will often complain of pain or paresthesias at the site of the animal bite. Animals transmitting the virus include. Furious form (80%) is commonly associated with hydrophobia, where viral multiplication in the salivary glands results in painful spasms of throat/larynx, especially when saliva production is increased associated with drinking or the thought of it. Dehydration is no longer likely because intravenous fluids can be given to completely replace what the hydrophobic patient cannot consume by mouth. Other complications of rabies include a paralytic form of the disease that progresses to quadriplegia (dumb rabies) in 20% of patients. With the classic form of the disease, the patient will also exhibit intermittent hyperactivity. Post-exposure prophylaxis consists of a single dose of rabies immunoglobulin and 3-4 doses of rabies vaccine. Patients have also been treated by inducing a coma (Milwalkee protocol) with some success even without post-exposure prophylaxis.
A 64-year-old female presents with progressive cognitive impairment, tremors, gait ataxia, and myoclonic jerks over the course of 6 months. There is no relevant family history. MRI of the head reveals a subtle increase in T2 signal in the basal ganglia bilaterally. EEG reveals disorganized background activity with periodic sharp-wave discharges that occur repetitively at 1-s intervals and extend over both sides of the head. There was also evidence of diffuse slowing and triphasic waves. The clinical picture is most consistent with which one of the following?
a. Alzheimer’s dementia
b. Friedreich’s ataxia
c. Multi-infarct dementia
d. Parkinson’s disease
e. Spongiform encephalopathy
e. Spongiform encephalopathy
The clinical, EEG and MRI findings are typical of a spongiform encephalopathy most probably due to Creutzfeldt-Jakob disease. This prion disease can be transmitted via infected nervous system tissue, including dura mater grafts, and occasionally via growth hormone preparations acquired from cadaver pituitary glands. CSF is usually normal, but may show slightly elevated protein, increased IgG, oligoclonal bands, and may contain a specific protein (14-3-3 proteinase inhibitor). Vascular causes are unlikely given the gradual deterioration and imaging findings. Friedreich disease may produce some dementia, but it is not a prominent part of the clinical deterioration and usually affects younger patients.
An 85-year-old woman has 3 days of gradually worsening fever and headache. She then develops blurry vision and a stiff neck. MRI with contrast has an enhancement pattern suggesting rhombencephalitis. CSF shows a mild pleocytosis with no organisms. All blood and CSF cultures are negative. Which one of the following is the most likely organism responsible for the patient’s condition?
a. Borrelia burgdorferi
b. E. coli
c. HTLV-1
d. Listeria monocytogenes
e. MRSA
d. Listeria monocytogenes
The presentation is highly suggestive of Listeria
monocytogenes meningitis. This infection commonly
develops in renal transplant recipients,
patients with chronic renal disease, immunosuppressed
persons, and occasionally in otherwise
unimpaired persons. It may also affect neonates.
This type of meningitis is not usually seen in older children. It may on occasion lead to intracerebral abscess formation. Third-generation cephalosporins are inactive against Listeria,and ampicillin and gentamicin are recommended therapy. Neither ampicillin nor penicillin alone is bactericidal.
A 75-year-old left-handed woman presented to the emergency room with what at first was thought to be a stroke. There is no clear history of recent infection. MRI head was performed and T1 + gadolinium, DWI and ADC map are shown. Which one of the following is the most appropriate next step?
a. Cerebral angiogram
b. Image guided attempted gross total resection
c. Lumbar puncture and oligoclonal bands
d. Stereotactic biopsy
e. Stereotactic needle aspiration
e. Stereotactic needle aspiration
Brain abscess are commonly due to hematological (e.g. pneumonia, endocarditis, dental work) or direct local spread of infection (e.g. mastoiditis, chronic otitis). They usually start from a microscopic focus of infection at the gray-white matter junction and takes the following course: early cerebritis 1-3 days, late cerebritis 4-9 days, early cap- sule 10-13 days, late capsule >14 days. As the infection develops, a cerebritis appears, and subsequently this focus of infection becomes necrotic and liquefies. Around the enlarging abscess, there is usually a disproportionately large area of edema. Mature abscess collagen capsule thinner on ventricular side, presence of dimple or small evagination for ring enhancing lesion should suspect abscess but this is not always distinguishable. Patient commonly present with headache, seizures, and focal neurological deficit. Streptococcal bacteria occur in more than half of all brain abscesses; Staphylococcus aureus most often occurs in patients who have had penetrating head wounds or have undergone neurosurgical procedures. Enteric bacteria (eg, Escherichia coli, Proteus, and Pseudomonas) account for twice as many abscesses as S. aureus. The important differentials of a ring enhancing brain lesion include primary tumor, metastasis, and abscess (although other causes are demyelination, maturing hematoma, and radiation necrosis). Due to the high mortality associated with intraventricular rupture of a brain abscess, emergency MRI should be per- formed to determine if the lesion is diffusion restricting (bright on DWI, dark on ADC) and thus likely to require emergency neurosurgical drainage. Although uncommon, diffusion restriction has been reported in metastases and glioblastomas and other modalities such as dynamic contrast-enhanced perfusion MRI may help distinguish between brain abscess and tumor; abscesses have a lower relative cerebral blood volume in their enhancing rim than gliomas.
During formation of an abscess capsule, when does necrosis begin?
a. Days 1-3
b. Days 4-9
c. Days 10-13
d. Days 14-20
e. Day 21 onwards
b. Days 4-9
Early cerebritis (days 1-3) is a poorly circumscribed lesion characterized by acute inflamma- tion and cerebral edema associated with bacterial invasion. Later (days 4-9), the zone of cerebritis expands, and necrosis develops, with pus forming at the center of the lesion. CT scanning reveals some ring enhancement with diffusion of contrast material into the necrotic center. The early capsule stage (days 10-13) demonstrates the establishment and maturation of a well-formed collagenous capsule associated with a reduction in the degree of cerebritis and some regression in the local edema. At the late capsule stage (day 14 and beyond), there is continued maturation of a thick capsule with extracapsular gliosis and dense ring enhancement with little contrast diffusion on CT scan. Capsule formation and ring enhancement on imaging studies are generally thinner and less complete on the ventricular side of the abscess. This situation is probably related to the relatively poor vascularity of the deep white matter and reduced migration of fibroblasts into the area. This thinner area of capsule predisposes to ventricular rupture of the abscess.
A 40-year-old ex-IV drug abuser presents to the emergency room with a seizure. CT head with contrast shows 3 cm diameter ring enhancing lesion periventricular location. MRI is performed and the lesion is bright on DWI and dark on ADC map. Which one of the following would be the appropriate next step in management?
a. Blood cultures and external ventricular
drain then start intravenous antibiotics
b. Craniotomy and excision of abscess then start intravenous antibiotics
c. Image-guided aspiration of abscess then start intravenous antibiotics
d. Endoscopic aspiration and irrigation
e. Real-time ultrasound-guided excision of
abscess and start intravenous antibiotics
b. Craniotomy and excision of abscess then start intravenous antibiotics
Image-guided craniotomy for excision of brain
abscess with its capsule has a lower recurrence
rate compared to aspiration methods. Excision
of brain abscesses is useful in: large (more than
2.5 cm) superficial abscesses, multi-loculated
abscesses, failure of resolution after several aspirations;
some posterior fossa lesions; some fungal
abscesses; post-traumatic abscesses with retained
bone fragments or foreign bodies; and gascontaining
abscesses, usually signifying the presence
of an associated CSF fistula. For surgical
excision of a brain abscess that has failed to
respond to aspiration and antimicrobial therapy
or is in a particularly dangerous location, such
as a posterior fossa abscess associated with edema,
mass effect, and impending or actual obstructive
hydrocephalus, image-guided craniotomy is
favored to excise the lesion, relieve the mass effect
on the brain stem, and reduce the chances of
recurrence. Excision is not the procedure of
choice in the cerebritis stage or in deep-seated
brain abscesses, especially in eloquent areas. During
the stage of cerebritis, antimicrobials are used
with serial neurologic examinations and imaging
studies to guide therapy. In most other settings,
however, surgical intervention is undertaken. In
the obtunded patient with a severe neurologic
deficit and an encapsulated lesion, surgery for
diagnosis and decompression is carried out emergently.
If multiple lesions are discovered, those
greater than 2.5 cm in diameter should be aspirated.
If all lesions are less than 2.5 cm and do
not exert mass effect, the largest or most accessible
one should be aspirated for culture.
A 37-year-old HIV positive male presents with headache, confusion, new right-sided weakness progressing over the previous week. He has been on highly active retroviral therapy for the last 10 years and not had any problems. On examination, his responses are slow and he has some difficulty sustaining attention. He has a right hemiparesis with increased reflexes on the right. FBC, U + E and CRP are normal. T1 contrast MRI is shown. Which one of the following organisms is the most likely cause?
a. Cryptococcus neoformans
b. Herpes zoster
c. Pneumocystic jerovecii
d. Toxoplasma gondii
e. Tuberculosis
d. Toxoplasma gondii
The timing of this presentation suggests that he has now developed AIDS. While fungal abscesses develop with unusual frequency in patients with AIDS, T. gondii is considerably more common than fungi as the cause of abscess formation. Cerebral toxoplasmosis usually presents as multiple ring-enhancing lesions in the basal ganglia, thalamus, or corticomedullary junction. Note the
“eccentric target sign,” which is shown best in the right parahippocampal lesion. Although this sign is not sensitive, it is fairly specific for toxoplasmosis. The combination of sulfadiazine and pyrimethamine is proper treatment for T. gondii infection. Neurosurgical drainage of the lesions is usually not indicated. The fungi that do produce abscesses in persons with AIDS are most often
Cryptococcus, Candida, Mucor,andAspergillus. Tuberculosis meningitis and abscesses are also common in immunocompromised individuals.
A 45-year-old renal transplant patient pre- sents with a 3-week history of worsening right headache, ear pain, and pyrexia. His medications include tacrolimus and cyclosporin. He is diagnosed with malignant fungal otitis externa and secondary osteomyelitis of the skull base. Which one of the following organisms is most likely?
a. Actinomyces
b. Aspergillus
c. Candida
d. Cryptococcus neoformans
e. Naegleria fowleri
b. Aspergillus
Fungal otitis exerna is usually caused by Aspergillus (black exudate), followed by Candida (cheesy white exudate) and Actinomyces. Although Aspergillus is the most common cause of fungal abscesses, it is a relatively uncommon cause of fungal meningitis or meningoencephalitis.
A 67-year-old with chronic sinusitis presents with severe frontal headache and change in smell. T1-gadolinium enhanced MRI head is shown. Which one of the following is most likely?
a. Basal meningitis
b. Cerebral abscess
c. Epidural abscess
d. Resolving hematoma
e. Subdural abscess
c. Epidural abscess
There is left subfrontal epidural fluid collection surrounded by an enhancing rim of thickened dura, which differentiates cranial epidural abscess from a sterile collection. They arise between the skull and the dura, usually in the frontal region, as a result of contiguous spread of infections from adjacent structures, such as the paranasal sinuses or the mastoid cells. It is associated with paranasal sinusitis, cranial osteomyelitis, or head trauma or occurs post-surgery. Risk factors for intracranial epidural abscess include prior craniotomy, head injury, sinusitis, otitis media, and mastoiditis. The bacteriology of these lesions is analogous to that of brain abscess. Generally, the epidural abscess is an indolent lesion when compared to subdural empyema. Neurologic symptoms and complications are rare, because the dura mater protects the brain parenchyma, and the tight adherence of the dura to the skull limits the spread. The most common presenting symptoms are fever, headache, and neurologic signs. Untreated, this parameningeal focus can extend intracranially and involve the dural venous sinuses, resulting in septic thrombophlebitis. The treatment consists of antibiotic therapy, usually in combination with surgical drainage to prevent progression to subdural empyema. Drainage of the epidural abscess can be done either by a minimally invasive approach or by a craniotomy with removal of infected bone. A higher rate of recurrence was reported after burr hole drainage. In preceding sinusitis, a combination of neurosurgical and ENT approaches are needed.
A 29-year-old ex-IVDU who previously underwent aspiration of a brain abscess and prolonged inpatient antibiotic course re-presents after several generalized tonicclonic seizures progressing into status epilepticus. Contrast CT head is shown. What is the next appropriate action?
a. Cerebral angiogram
b. Decompressive craniectomy
c. External ventricular drain
d. Lumbar drain
e. Palliative care
c. External ventricular drain
Axial CT shows dilated lateral ventricles that contain intermediate attenuation debris suggestive of pyogenic ventriculitis, with a rim of lowattenuation interstitial edema surrounding the ventricles. The intraventricular rupture of a brain abscess occurs with progressive growth of the lesion. As the pus increases, the abscess expands toward the ventricle and may rupture, resulting in the sudden, catastrophic deterioration of the patient. The diagnosis is confirmed by the presence of hydrocephalus and enhancement of the ventricular walls. Immediate ventricular drainage, intraventricular instillation of antibiotics, evacuation of the remaining abscess, and systemic antibiotic therapy are still associated with a management mortality rate of greater than 80%
A 27-year-old immigrant from South America presents with a generalized seizure. After awakening, he relates that he has had two or three episodes of unexplained loss of consciousness in the past 2 years. He has otherwise been healthy and worked as a farmer. His examination is normal. MRI head was performed and T2 and T1 +GAD images are shown. What is the most likely organism?
a. Histoplasma
b. Mucor
c. Shistosoma mansonii
d. Taenia solium
e. Toxoplasma gondii
d. Taenia solium
MRI shows extensive parenchymal and subarachnoid
cysticercosis. Most of the lesions are in the
vesicular stage showing thin-walled cysts with little
or no enhancement and a scolex (worm head)
in the center of the cyst. Cysticercosis is produced
by the larval form (cysticercus) of the pork tapeworm,
Taenia solium. This is the most common
neurological infection throughout the world,
occurring most commonly in South America,
Southeast Asia, and Africa. It is transmitted by
fecal-oral contact; tapeworm eggs hatch in the
human GI tract, invade the bowel mucosa, and
migrate throughout the body, particularly into
CNS, muscle, eye, and subcutaneous tissues.
Cysticercal infection of muscles produces a nonspecific
myositis. Brain involvement may lead to
seizures. The lesions in the brain may calcify
and often appear as multiple small cysts spread
throughout the cerebrum. Treatment of neurocysticercosis
depends on whether the cyst is dead
(antiseizure medication) or viable. Viable cysts in the presence of vasculitis/arachnoiditis/encephalitis, immunosuppressant therapy is usually given before anticystercal drugs (albendazole and praziquantel). Neurosurgical management may be indicated when intraventricular or racemose cysts cause hydrocephalus.
A 35-year-old woman has progressive numbness of the right arm and difficulty seeing objects in the right visual field. She is known to be HIV positive, but has not consistently taken medications in the past. On examination, she appears healthy, but has a right homonymous hemianopsia and decreased sensory perception in her right upper extremity and face. Her CD4 count is 75 cells per μL, and her MRI is consistent with a demyelinating lesion of the left parieto-occipital area. CSF PCR for JC virus is positive. Which one of the following is the most appropriate treatment in this case?
a. Amphotericin B
b. Fluconazole
c. Highly active antiretroviral therapy (HAART)
d. Intravenous acyclovir
e. Intravenous rifampicin
c. Highly active antiretroviral therapy (HAART)
Progressive multifocal leukoencephalopathy is caused by the JC virus, which is a double-stranded DNA virus transmitted via respiratory droplets. MRI demonstrates widespread hyperintense signal change in the left corona radiate with typical involvement of the subcortical U fibers, and DWI shows a hyperintense edge of the lesion medially reflecting zones of active demyelination. The prognosis is poor, but HAART has been known to be effective in improving survival.
A 12-year-old boy has left body weakness. A brain magnetic resonance imaging (MRI) scan reveals a polycystic lesion. Which one of the following is most likely?
a. Diphyllobothrium latum
b. Echinococcus
c. Schistosoma hematobium
d. Schistosoma japonicum
e. Taenia solium
b. Echinococcus
Echinococcosis is usually acquired by ingesting material contaminated with fecal matter from sheep or dogs. Children are more likely to develop cerebral lesions than adults, but people at any age may develop this encephalic hydatidosis, which entails the development of a major cyst with multiple compartments in which smaller cysts are evident. This hydatid cyst of the brain behaves like a tumor and may become massive enough to cause focal deficits.
